He said D.I, meaning a D.I box I imagine. It's basically a preamp that converts the signal into a form that the PA can use. I've used one in the studio for recording bass without an amp before and it sounds great in that context

My SoundcloudAlways up for some C4C, been compared to Frank Turner, The Cure's Robert Smith and Bruce Springsteen so check out my stuff if you like the sound of that